Currently, with the development of the electric vehicle industry, higher requirements are imposed on a jack due to the using of a large current, for example, a low plugging and unplugging force for meeting people's frequent plugging and unplugging requirement in charging; a low contact resistance for alleviating the temperature rising issue caused by the large current.
A conventional electric connector contact member includes a single sheet revolving hyperbolic wire spring jack, which utilizes a group of elastic wires arranged into a single sheet revolving hyperbolic structure to evenly wrap around a surface of a pin inserted therein, belonging to a multiple wire wrapping contact. The jack contact adopting this wire spring structure consists of four parts including an inner sleeve, an outer sleeve, a rear sleeve and elastic wires. A group of elastic wires arranged into a single sheet revolving hyperbolic structure are coaxially nested in an inner sleeve tube, and two ends of the wires mounted in the inner sleeve tube protrude out of openings at two ends of the inner sleeve tube, and curve backwards on an outer cylindrical surface of the inner sleeve tube. A curved portion is clamped by inner cylindrical surfaces of a front sleeve and the rear sleeve and the outer cylindrical surface of the inner sleeve. The front sleeve and the rear sleeve are connected integrally into an outer sleeve by being pressed.
The wire spring jack has following deficiencies.
1. With the sleeve connection, the contact resistance is large, and a pulling resistance is poor, and the front and rear sleeve are extremely apt to be disengaged from the pressing point due to a pulling force, causing connecting fault and incident. 2. The structure is complex, the number of parts to be assembled is large and the volume cannot be further reduced, which is disadvantageous for the development of miniaturization and densification. 3. The manufacturing process is complex; the precision requirement is high, causing a low product qualification rate and an improved cost. 4. The elastic wires cannot be arranged to be thick in a limited space, and each wire cannot withstand a large current surge. 5. The phenomena of breaking of the elastic wires is unavoidable during use. 6. The plugging and unplugging force is large. Since the copper wires are fixed to two ends of a thin-walled tube and are immovable, a large plugging and unplugging force is therefore required.